Hematological and mineral alterations associated with subclinical mastitis in dairy cattle following the foot-and-mouth disease outbreak in West Java, Indonesia.

Background and aim: Subclinical mastitis (SCM) remains a pervasive and economically significant disease in the dairy industry worldwide. In Indonesia, its prevalence has been amplified by poor management and environmental conditions, with incidence further exacerbated by the 2022-2023 foot and mouth disease (FMD) outbreak. This study aimed to investigate the hematological and blood mineral profiles of dairy cows with varying severities of SCM in West Java, thereby identifying disease-associated alterations that may improve detection and management strategies.

Materials and methods: A total of 155 blood samples and 620 milk samples were collected from Holstein-Friesian dairy cows across five high-density dairy regions in West Java between July and November 2024. Somatic cell counts (SCC) were determined using the Breed method and cows were categorized into three groups: Group A (0-100 × 10³ cells/mL), group B (100-400 × 10³ cells/mL), and group C (>400 × 10³ cells/mL). Hematological profiles were assessed using an automated analyzer, while serum calcium (Ca) and phosphorus (P) concentrations were measured through atomic absorption spectrophotometry. Data were analyzed using analysis of variance, Kruskal-Wallis, and Spearman's correlation tests.

Results: Elevated SCC was associated with significant increases in total leukocytes, neutrophils, and lymphocytes (p < 0.05), with a higher prevalence of leukocytosis (26.23%), neutrophilia (15.15%), and lymphocytosis (21.88%) observed in group C cows. Blood Ca levels increased significantly with SCC (r = 0.31, p < 0.01), despite overall hypocalcemia being widespread (44.78%-73.81%). Erythrocyte counts, hemoglobin, and hematocrit showed declining trends with rising SCC, though not statistically significant. No significant correlation was observed between SCC and P levels.

Conclusion: Increased leukocyte, neutrophil, lymphocyte, and Ca levels are strongly linked to elevated SCC in SCM. These blood-based parameters, particularly leukocyte and Ca profiles, show promise as alternative diagnostic indicators under low-resource conditions where SCC testing is limited. This study presents one of the most comprehensive datasets on post-FMD SCM in Indonesian dairy herds, highlighting the potential for developing low-cost diagnostic markers to enhance early detection and improve herd management.